Method of operating dynamo-electric machines.



No. 654,595. Patented July 3|, I900.

' E. J. BERG. METHOD OF OPERATING DYNAMO ELECTRIC MACHINES.

(Application filed May 26, 1900.)

. (No' Model.)

r W E a 8 nB Q a 9cm. m E m mm rrn STATES PATENT ERNST J. BERG,-OFSOHENECTADY, NEW YORK, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF NEYVYORK.

METHOD OF OPERATING DYNAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of- Letters Patent No. 654,595, dated July31, 1900.

. Application filed May 26,1900. :SorialNo.18,034. on, model) To aZZwhom it may concern.-

Be it known that I, ERNST J. BERG, a citizen of the United States,residing at Schenectady, county of Schenectady, State of New York,

' have invented certain new and useful Improvements in Methods ofOperating Dynamo Electric Machines, (GaseNo. 1,219,) of which thefollowing is a specification. My present invention relates to the opera-IO tion of dynamo-electricmachines of the synchronous type, andcomprises a method of adjusting the angular position of the rotatingmember of such a machine. The application of this method is of use inmany relations; r5 but I have found it of particular value in caseswhere it is desired to operate frequencychanging motor-generator sets inmultiple with each other. Motorgenerators of this character necessarilyhave a different numher of poles on the motor than on the generator, byreason of which fact it is possible for the motor ends of the sets to bein synchronism at certain relative positions of their rotating members,while at the same instant the 2 5 generator ends have such relativephase relations as to prevent their being thrown in multiple with eachother.

My invention in its principle, as well as mode of application, will bebetter under--' stood by reference to the following description, takenin connection with the accompanying drawing, while its novel featureswill be particularly pointed out in the appended claims.

The drawing represents two motor-genera tor sets together with thecooperatin g mains, eXciter-circuits, and other features. At 1 and 2,respectively, I have indicated in diagram a generator and a motorcomprising a single motor-generator set,'the motor and generator beingsupposed to have their rotating members mounted upon the same shaft orupon shafts mechanically coupled together, the dotted lines 3 signifyingsome 5 rigid mechanical connection between the machines.

Three-phase supply-mains are shown at 4,

5, and 6, to which mains current of some suitable frequency-as, forinstance, twenty-five 5o cycles-is supplied. This current is transmittedto the armature 7 of the motor 2 by leads 8 9 10, connected to the mains4 5 6 through the usual switches 11, 12, and 13. In a similar manner thearmature-winding of the generator 1 is connectedthroughcollector-rings14 and sliding contacts '15 to leads 16 17 18,branching from another set of threephase mains 19, 20, and 21. The usualmainswitches 22, 23, and 24 are provided in circuit with the leads 16 1718.

The field windings of the motor and generator, respectively, areindicated at 25 and 26 and are supplied with direct current throughbranch leads 27 and 28, connected to the em citer-circuit 29, whichleads to some suitable source of direct current. (Not shown.) Thefield-circuits of the machines are provided with circuit opening andclosing switches 30 and 31.

The motor 2 is shown with eight poles, while the generator 1, which isdriven by the motor, is provided with twenty poles. The ratio offrequencies in the two machines is therefore as eight to twenty, andsince twenty-five-cycle current issupposed to be supplied to the motor 2it follows that the current produced by the generator 1 will beapproximately sixty cycles.

"At 32 and 33 I have shown amotor and a generator rigidly coupledtogether, as by means of a shaft, (indicated in dotted lines at 34,) thecombination of machines constituting another motor-generator set exactlysimilar to that already described, the motor being, as in the firstinstance, provided with eight poles and the generator with twenty. Thegenerator end of this last-mentionedmotorgenerator set is adapted to beconnected to the mains 19, 20, and 21 through mainswitches, (indicatedat 35, 36, and 37.) In a similar manner the motor 32 may be connected tothe mains 4 5 6 by closing the switches 38 39 40, connected in the leadsto the motorarmature. The usual synchronizing-lamps are arranged acrosstwo of the switches of each set of leads, one set of synchronizinglampsbeing indicated in the drawings at 42, this set serving to indicatesynchronism of the motor, while another setof' synchroniz ing-lamps isshown at 43, the latter set acting to indicate synchronism of'thegenerator. It is to be understood, of course, that the motor-generatorset 1 2 may be similarly supplied with synchroniZing-lamps or similardevices, if desired.

The field-circuit at of the motor 32 is supplied with direct currentfrom the exeitermains 29 and is connected thereto through areversing-switch of any suitable form-such, for example, as indicateddiagrammatically at- 45. The field-circuit 46 of the generator 33 isalso connected to the eXciter-mains 29, as shown, and, if desired, areversing-switch may also be included in this field-circuit.

Supposing now the motor-generator set 1 2 be connected to the respectivesets of mains t 5 6 and 10 2O 21, whereby current of one frequencysupplied from one of the sets of mains will be converted into adifferent frequency and supplied to the other set of mains, then, owingto the rigid mechanical connection between the motor and generator ofthe motor-generator set, it will be obvious that there would be acertain definite relation'between the sequence of phases in the twocircuits, depending upon the angle at which the armatures of the twomachines are coupled together. Thus, as a concrete example, suppose anarmature-conductor connected to the lead 9 to be in a position under thepole 47 at some particular instant. The armature of the generator 1 mayat this instant occupy any selected angularposition, depending upon themanner in which it is coupled to the armature 7. For example, let thetwo armatures be coupled together so that an armature-conductorconnected to the lead 17 of the generator 1 lies under the pole 48 ofthe generator at the same instant that the aforesaid armature-conductorof the motor lies under the pole 47. If the motor and generator 32 and33 occupy the same relation to each other as the motor 1 and generator2, then the two sets may be thrown in parallel with each other at aninstant when the motors are in synchronism with each other and thegenerators also. This may be done when a con ductor connected to themain 39 and lying upon the armature 49 of the motor 32 is in a position,for example, under the pole 50, while at the same time anarmature-conductor-of the generator 33, connected to the lead 36, liesunder the pole 51. In this arrangement, which is specified merely by wayof example, it will be seen that if the poles 47 50 are of the samepolarity and the poles 18 51 also of like polarity to each other thenthe generator electromotive forces will be in phase with each other atthe same time that the electromotive forces of the motors are in phase,thereby permitting the motor-generator sets to be thrown in multiplewith each other. Supposing, however, that the motorgenerator set 32 33catches in synchronism not at the instant supposed, but in a positiondisplaced by ninety degrees. The conductor upon the armature t9, takenby way of illustration, will then be lying under the pole 52, which isof the same polarity as the pole 50.

The motor electromotive forces of the machines 2 and will then be insynchronism with each other, the same as when the conductor referred towas under the pole 50. It will be noted, however, that the conductor onthe armature of the generator 33, which heretofore lay under the pole51, is now in a position under the pole 53 of opposite polarity, byreason of which the electromotive forces which would be impressed uponthe mains 35, 36, and 37 by the generator 33 are no longer in phase withthe electromotive forces in1- pressed upon the leads 1G 17 18 by thegen-.

erator 1, so that the two generators cannot be thrown into multiple witheach other even though their respective motors are operating insynchronism. To overcome this dit'ticulty,I make use of some meansforcausing the motor to slip until a position is reached when bothmotors and generators can be thrown into multiple with each other.Various means may be employed for accomplishing this result,and in thedrawing I have shown one which is particularly useful because of itssimplicity and low first cost. This consists of the reversingswitch 45,placed in circuit with the field M- of the motor. The reversing-switchis first moved until the field is open-circuited. The motor thencontinues to run synchronously, but excites its own held by armaturereaction. A. further movement of the revcrsing-switch sends currentthrough the field-winding in the opposite direction, thus reversing thefield and causing the armature to slip back a pole. A repetition of thesuccessive reversals of the field causes the armature to slip from poleto pole, thereby causing a relative movement between the armature of thegenerator 33, driven thereby, and the armature of the generator 1 of theother motor-generator set. By causing the armature of themotor-generator set 32 and 33 to slip sufficiently the relation of thearmatures of the two sets may be made such that they may be thrown inmultiple with each other, as will readily be seen. The phase-lamps 12and L3 serve to indicate when two sets are in synchronism, thephase-lamps going out when this point is reached.

As my invention relates more particularly to a method of operation, I donot wish my claims to be limited in their application to the use of anyparticular apparatus for performing the operations specified.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is-- 1. The method of adjusting the angular position ofthe rotating member of a synchronous dynamo-electric machine whichconsists in causing said member to slip until the desired angularposition is secured and then checking any further slip.

2. The method of connecting motor-generators in multiple with each otherwhich con sists in causing one set to slip from synchro nism until bothof its members come into synchronism at the same instant with the corresponding members of another motor-genes ator set, and then causing theinotor-generher ofasynchronous dynamo-electric machine to slip, whichconsists in successively reversing its field.

In witness whereof I have hereunto set my hand this 24th day of May,1900.

ERNST J. BERG.

Witnesses:

BENJAMIN B. HULL, MABEL E. JAooBsoN.

